Végétation et climat dans les forêts du sud-ouest Cameroun depuis 4770 ans BP : analyse pollinique des sédiments du lac Ossa

L'analyse palynologique détaillée d'une carotte prélevée dans le lac Ossa, situé au coeur de la forêt littorale atlantique du SW Cameroun, apporte de nouvelles informations sur l'histoire botanique et climatique de cette région depuis 4 770 ans BP. La microflore pollinique inventoriée, riche et très diversifiée, indique la permanence de l'environnement forestier durant toute cette période. De 4 770 à 2 730 BP, les forêts Biafréenne et afromontagnarde sont bien représentées dans les spectres polliniques. Puis vers 2 730 BP (âge estimé), une modification majeure du paysage apparaît. La forêt de type primaire est remplacée par une forêt perturbée riche en arbres pionniers (#Alchornea, #Macaranga). Ultérieurement on note l'extension du palmier à huile (#Elaeis guineensis$) qui culmine vers 1 600 BP. (Résumé d'auteur

Effect of Transgene Location, Transcriptional Control Elements and Transgene Features in Armed Oncolytic Adenoviruses

Clinical results with oncolytic adenoviruses (OAds) used as antitumor monotherapies show limited efficacy. To increase OAd potency, transgenes have been inserted into their genome, a strategy known as "arming OAds". Here, we review different parameters that affect the outcome of armed OAds. Recombinant adenovirus used in gene therapy and vaccination have been the basis for the design of armed OAds. Hence, early region 1 (E1) and early region 3 (E3) have been the most commonly used transgene insertion sites, along with partially or complete E3 deletions. Besides transgene location and orientation, transcriptional control elements, transgene function, either virocentric or immunocentric, and even the codons encoding it, greatly impact on transgene levels and virus fitness

Reconfigurable swarms of nematic colloids controlled by photoactivated surface patterns

Different phoretic driving mechanisms have been proposed for the transport of solid or liquid microscopic inclusions in integrated chemical processes. It is now shown that a substrate that was chemically modified with photosensitive self-assembled monolayers enables the direct control of the assembly and transport of large ensembles of micrometer-sized particles and drops that were dispersed in a thin layer of anisotropic fluid. This strategy separates particle driving, which was realized by AC electrophoresis, and steering, which was achieved by elastic modulation of the nematic host fluid. Inclusions respond individually or in collective modes following arbitrary reconfigurable paths that were imprinted by irradiation with UV or blue light. Relying solely on generic material properties, the proposed procedure is versatile enough for the development of applications that involve either inanimate or living materials

Chiral-symmetry selection in soft monolayers under vortical flow

Herein, we report and interpret a new chiral-selection phenomenon in the orientational ordering of soft-assembled domains that arise spontaneously in Langmuir monolayers of an azobenzene derivative at the air/water interface. The orientational chirality of isolated sub-millimeter domains was unambiguously assessed by optical microscopy. The selection process, quantified by using an enantiomeric excess parameter, was controlled by stirring the aqueous subphase. We have studied the dependence of this process on stirring rate and handedness, stirring time, temperature, and on the initial state of the monolayer. The influence of the concomitant cis/trans isomerization on the reported chiral-selection process is also discussed

Arming Oncolytic Adenoviruses: Effect of Insertion Site and Splice Acceptor on Transgene Expression and Viral Fitness

Oncolytic adenoviruses (OAds) present limited efficacy in clinics. The insertion of therapeutic transgenes into OAds genomes, known as "arming OAds", has been the main strategy to improve their therapeutic potential. Different approaches were published in the decade of the 2000s, but with few comparisons. Most armed OAds have complete or partial E3 deletions, leading to a shorter half-life in vivo. We generated E3+ OAds using two insertion sites, After-fiber and After-E4, and two different splice acceptors linked to the major late promoter, either the Ad5 protein IIIa acceptor (IIIaSA) or the Ad40 long fiber acceptor (40SA). The highest transgene levels were obtained with the After-fiber location and 40SA. However, the set of codons of the transgene affected viral fitness, highlighting the relevance of transgene codon usage when arming OAds using the major late promoter

Interaction of Cupidin/Homer2 with two actin cytoskeletal regulators, Cdc42 small GTPase and Drebrin, in dendritic spines

<p>Abstract</p> <p>Background</p> <p>Homer is a postsynaptic scaffold protein that links various synaptic signaling proteins, including the type I metabotropic glutamate receptor subunits 1α and 5, the inositol 1,4,5-trisphosphate receptor, Shank and Cdc42 small GTPase. Overexpression of Homer induces changes in dendritic spine morphology in cultured hippocampal neurons. However, the molecular basis underpinning Homer-mediated spine morphogenesis remains unclear. In this study, we aimed to elucidate the structural and functional properties of the interaction between Cupidin/Homer2 and two actin-cytoskeletal regulators, Cdc42 small GTPase and Drebrin.</p> <p>Results</p> <p>Cupidin/Homer2 interacted with activated Cdc42 small GTPase via the Cdc42-binding domain that resides around amino acid residues 191–283, within the C-terminal coiled-coil domain. We generated a Cupidin deletion mutant lacking amino acids 191–230 (CPDΔ191–230), which showed decrease Cdc42-binding ability but maintained self-multimerization ability. Cupidin suppressed Cdc42-induced filopodia-like protrusion formation in HeLa cells, whereas CPDΔ191–230 failed to do so. In cultured hippocampal neurons, Cupidin was targeted to dendritic spines, whereas CPDΔ191–230 was distributed in dendritic shafts as well as spines. Overexpression of CPDΔ191–230 decreased the number of synapses and reduced the amplitudes of miniature excitatory postsynaptic currents in hippocampal neurons. Cupidin interacted with a dendritic spine F-actin-binding protein, Drebrin, which possesses two Homer ligand motifs, via the N-terminal EVH-1 domain. CPDΔ191–230 overexpression decreased Drebrin clustering in the dendritic spines of hippocampal neurons.</p> <p>Conclusion</p> <p>These results indicate that Cupidin/Homer2 interacts with the dendritic spine actin regulators Cdc42 and Drebrin via its C-terminal and N-terminal domains, respectively, and that it may be involved in spine morphology and synaptic properties.</p

Photonic quantum state transfer between a cold atomic gas and a crystal

Interfacing fundamentally different quantum systems is key to build future hybrid quantum networks. Such heterogeneous networks offer superior capabilities compared to their homogeneous counterparts as they merge individual advantages of disparate quantum nodes in a single network architecture. However, only very few investigations on optical hybrid-interconnections have been carried out due to the high fundamental and technological challenges, which involve e.g. wavelength and bandwidth matching of the interfacing photons. Here we report the first optical quantum interconnection between two disparate matter quantum systems with photon storage capabilities. We show that a quantum state can be faithfully transferred between a cold atomic ensemble and a rare-earth doped crystal via a single photon at telecommunication wavelength, using cascaded quantum frequency conversion. We first demonstrate that quantum correlations between a photon and a single collective spin excitation in the cold atomic ensemble can be transferred onto the solid-state system. We also show that single-photon time-bin qubits generated in the cold atomic ensemble can be converted, stored and retrieved from the crystal with a conditional qubit fidelity of more than $85\%$. Our results open prospects to optically connect quantum nodes with different capabilities and represent an important step towards the realization of large-scale hybrid quantum networks

Lamellarin D bioconjugates II: synthesis and cellular internalization of dendrimer and nuclear location signal derivatives

The design and synthesis of Lamellarin D conjugates with a nuclear localization signal peptide and a poly(ethylene glycol)-based dendrimer are described. Conjugates 1-4 were obtained in 8-84% overall yields from the corresponding protected Lamellarin D. Conjugates 1 and 4 are 1.4 to 3.3-fold more cytotoxic than the parent compound against three human tumor cell lines(MDA-MB-231 breast, A-549 lung, and HT-29 colon). Besides, conjugates 3, 4 showed a decrease in activity potency in BJ skin fibroblasts, a normal cell culture. Cellular internalization was analyzed and nuclear distribution pattern was observed for 4, which contains a nuclear localization signalling sequence

Genetic and molecular characterization of bud dormancy in apple: deciphering candidate gene roles in dormancy regulation.

Dormancy is an adaptive mechanism that enables plants to survive unfavorable climatic conditions, for example during winter, and allows flowering to occur only when the conditions are more permissive, typically in spring